Inhibition of FSP1 and BCL-2 synergizes with DMF treatment. (A) SU-DHL-6 and DOHH2 cells were transplanted into zebrafish embryos. Tumor formation in animals treated with either solvent or 5 μM DMF was quantified by microscopy after 3 days (n ≥ 21). DMF treatment significantly reduced the frequency of tumor-bearing animals (P = .001 for SU-DHL-6; P = .043 for DOHH2). (B) Representative images of transplanted zebrafish embryos after solvent or DMF treatment. The respective tumor cells were fluorescently labeled and visualized by microscopy. The pictures on the right represent magnified sections of the zebrafish embryos. Scale bar, 100 μm. (C-D) SU-DHL-6 or HBL-1 cells were treated with DMF alone (top panels) or in combination with either FSP1 inhibitor (iFSP1) (C) or ABT-199 (D) (bottom panels). Cell survival was quantified by MTS assay after 24 (C) or 72 (D) hours . The combination index (CI) for DMF and iFSP1 in SU-DHL-6 is ≤0.55, and for DMF and ABT-199 in HBL-1 is ≤0.75. (E-F) HBL-1 (E) or VFN-D1 patient-derived (F) xenograft mice were treated either with vehicle, ABT-199, DMF, or the combination of ABT-199 and DMF, as indicated. Tumor volume was quantified by caliper measurements up to 14 days after start of the treatment. Each group consists of ≥7 animals. Statistical significance was calculated by the comparison of each treatment group with the vehicle control. Data are representative of ≥3 independent experiments (A-D). *P < .05, ***P < .001.